Promptr

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- **Added:** Automatic context handling for arguments
- **Added:** on_exit handler for states
- **Fixed:** AmbiguousCommand incorrectly thrown in some circumstances

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- **Added:** Ability to create a prompt, commands, groups, and states
- **Added:** Arguments can be added with suggestions
- **Added:** Command completion when run as a prompt loop
- **Known Bug:** Arguments are not validated
- **Known Bug:** Command completion fails on partial commands and after arguments